Although, in many physiological systems a cascade of events have been proposed between stimulation and response, little is understood concerning the stimulus-secretion "coupling" process occurring in renin release from the kidney cortex. The isolated superfused glomeruli preparation has been recently developed to study renin release in vitro. This technique permits monitoring the release of renin from isolated renal cortical tissue while varying media constituency, temperature and perfusion rate. Sincerenin release from this isolated tissue is readily stimulated by, for example beta agonists, it is possible to study the process occurring between stimulus and renin release. I propose to study the need for metabolic energy and divalent cations for this stimulated renin release. Also, the role of cAMP and prostaglandins and their intermediates in this coupling process is to be investigated. Finally, I propose to investigate the hypothesis that this "coupling" process alters renin release through changing membrane permeability, and consequently, cell volume.